How does bdf command measure sizes for RAID devices?

[Mott Given]

How does the "bdf" command take into account RAID devices and BCV's? For example, if disk mirroring was being used for 100 GB of files, would bdf output show 100 GB of file space used, or would it show 200 GB being used? I'm thinking about EMC RAID devices that we use, but I don't have the permissions to run the EMC commands and the sysadms are too busy to run them for me.


Mott Given

[Denver Osborn]

bdf won't show any info to help you with the H/W RAID. It will only show what the filesystem is reporting as used, the RAID is happing at another level that bdf won't know about... The RAID info would have to be confirmed w/ using your EMC commands to check the array.

-Denver

[Mott Given]

So in my example with the hypothetical 100 GB of files being mirrored, woud "bdf" show 100 GB being used or 200 GB being used?

Mott

[Denver Osborn · Accepted solution]

bdf would show 100GB for the total size of the filesystem.... if the EMC was mirroring that, bdf wouldn't know about it. bdf can only see the filesystem that is on the device.

So if you have a 100GB lun that the operating system sees, and the EMC has set aside another 100GB to mirror it... the OS does not know about it... it only knows about the 100GB lun that it can see...

-Denver

[Mott Given]

Thanks for your help!

Mott